Evaluation of bilateral minimum thickness of normal corneas based on Fourier-domain optical coherence tomography.

PURPOSE

To determine the normative ranges and various aspects of the relationship between the minimum corneal thicknesses (MCT) in fellow eyes and the location of the MCT in relation to the central cornea using Fourier-domain optical coherence tomography (OCT).

SETTING

Tertiary care ophthalmic hospital, Chennai, India.

METHODS

In this cross-sectional observational trial, both eyes of consecutive healthy young subjects with a low refractive error and no clinical or topographic evidence of corneal disorders had bilateral pachymetric assessment with a Fourier-domain OCT platform (RTVue). The MCT, central corneal thickness (CCT), and x-y coordinates of the MCT location were noted.

RESULTS

The CCT and MCT followed a normal distribution with a good correlation. The difference between CCT and MCT was approximately 5 microm in right eyes and left eyes (P<.05 for both). The difference in CCT was the best predictor of the difference in MCT. The mean distance from the center (0.63 mm +/- 0.13 [SD], right eyes; 0.66 +/- 0.17 mm, left eyes) was well correlated. The MCT points in fellow eyes tended to be symmetrical along the vertical midline. The mean angular distance between mirror-superimposed MCT points was 20.54 +/- 17.6 degrees and the mean linear distance, 0.25 +/- 0.17 mm.

CONCLUSIONS

The findings establish normative MCT pachymetry data and location using Fourier-domain OCT. The MCT and CCT points, although symmetrical, differed significantly in location and magnitude and should be evaluated separately in normal eyes and eyes with disease.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned. Additional financial disclosures are found in the footnotes.